Portable dental furnace.



PATENTED FEB; 13, 1906.

F. S. BELYBA.

PORTABLE DENTAL FURNACE.

APPLICATION FILED mm: 2, 1904. RENEWED JAN. 9, 1906.

wo 'zass as,

FREDERICK S. BELYEA, OF BROOKLINE, MASSACHUSETTS.

PORTABLE DENTAL FURNACE.

Specification of Letters Patent.

Patented Feb. 13, 1906.

Application filed June 2, 1904. Renewed January 9, 1906. Serial No.295,258.

To all whom it warty concern.-

Be it known that I, FREDERICK S. BELYEA, a citizen of the United States,and a resident of Brooklin'e, county of Norfolk, State of Massachusetts,have invented an Improve? ment in Portable Dental Furnaces, of which thefollowing description, in connection with the accompanying drawings, isa specification, like letters on the drawings representing like parts.

This invention has for its object the production of a compact, simple,and efficient portable dental furnace particularly adapted for makingporcelain fillings. In the process of making such fillings a very thingold or platinum lining is burnished into the properly-prepared cavityof the tooth, forming a matrix the exact shape of the cavity. Such.matrix is carefully removed, filled with a moist porcelain compound, andbaked, and when the baking is completed the matrix is stripped off andthe hard filling is cemented into the cavity. The baking requires anintense heat, while the porcelain must be protected from direct contactwith the flame, and various forms of furnaces have been devised for thepurpose; but so far as I am aware they are comparatively large and heavyand require some special form of blowpipe or heating apparatus to raisethe temperature to the proper baking-point.

In my present invention I have devised a furnace which is arranged on asuitable handle so that it may be held in the hand of the operator andreadily turned in various directions during the baking, so that at anyin stant the contents may be observed and the condition of the bakingfilling noted. A common gas-flame from a Bunsen or other burner may bereadily used with the aid of a blowpipe, the whole apparatus being ofgreat simplicity in construction, of light weight, and capable of thegreatest ease in handling.

The various novel features of my invention will be fully described inthe subjoined specification and particularly pointed out in thefollowing claims.

Figure 1 is a perspective view of a dental furnace and its handleembodying my. invention looking into the open end or mouth of themuffle. Fig. 2 is a front elevation thereof. Fig. 3 is a side elevationof the furnace, the handle being broken off. Fig. 4 is a top or planview thereof, and Fig. 5 is a longitudinal section of the furnace on theline 5 5, Fig. 2.

In accordance with the present embodiment of my invention the furnacecomprises a muffie having an open mouth and a casing inclosing themufiie and having an open bottom and rear end, with an outlet in its topfor the escape of flame and to induce a current of the burning gas orflame around the muffle. Means are provided to attach the muffle to theclosed front end of the casing in such manner that the muflie may bereadily attached to or removed therefrom, and a suitable handle to begrasped by the operator is secured to the casing.

The muffle, preferably made of platinum, comprises a flat bottom 1, acurved top and side portion 2, and a closed rear end 3 of suchdimensions as will conveniently accommodate work of the characterspecified, the front end or mouth 4 of the mufiie being open. A metallicshell-like outer casing 5, of German silver or other suitableheat-resisting material, is made in substantially semicylindrical formto inclose the muffle and leave a clearance between them, the bottom andrear end of the casing being open, as shown clearly in Fig. 5, and avent-opening 6 is made in the top of the casing at or near its frontend. The frontend of the casing is closed by a plate 7, having anopening therein conforming to the perimeter of the mufi'le and extendinglaterally beyond the front edge of the casing, the latter having lugs 9inserted in slits 10 in the plate and bent over, as in Figs. 1 and 2,thereby firmly connecting the body of the easing and its closed end. Ihave herein shown the plate 7 provided with forwardly-extended ears 8,adapted to frictionally engage and hold the sides of the muffle wheninserted in the opening of said plate, the portion of the muffleprojecting in front of the plate being pinched up, as at 1.1, tocooperate with the ends of the ears, and thereby prevent any twistingmovement of the muffle. Several indentations 12 are preferably made inthe muffle-bottom 1, just inside the plate 7, to assist in securingmuffle and casing together, the means dedescribed for connecting theparts permitting ready insertion or removal of the muflie, if necessary.Below the mouth of the muffle the plate is provided with an ear 13,which projects in front of the mouth of the muffle at the bottomthereof, constituting a shield to prevent any flame from passing beneaththe plate 7 and into the mouth of the muffle.

I have provided ahandle 14 for the furnace, (shown as attached to theend plate 7 of the casing) by which the operator holds the fur naceduring the baking operation.

When a filling has been prepared, it is placed in the muffle and theoperator grasps the handle 14 and holds the furnace over the flame of asuitable blowpipe, so that the flame envelops the muffle between it andthe casing, the arrows in Fig. 5 showing the direction of the flame. Theoutlet 6 permits the flame to escape at the top of the casing adjacentits front closed end, so that the bottom, sides, and rear closed end ofthe muffle will be enveloped by the flame, a strong heat being securedat the back of the muffle, where the filling to be baked is placed. Theoperator can turn or tip the furnace, as desired, during the baking andcan at all times observe the progress of the baking through the openmouth of the muffle, the shield 13 pre venting the entrance of any flameinto the muffle, as direct contact of flame with the filling wouldinjure the latter.

The weight of the furnace is so light that its manipulation is effectedwith the greatest facility by the operator, and no special form ofheating apparatus is required.

Having fully described my invention, what I claim as new, and desire tosecure by Letters Patent, is

1. In a portable dental furnace, a metallic muffle having an open mouth,and a shelllike outer casing inclosing the muffle with a clearancebetween them and entirely open at its rear end and bottom, the mufflebeing attached to and supported by the closed front end of the casing.

2. Ina portable dental furnace, a metallic muffle having an open mouth,a thin, shell- -like casing inclosing the muflle with a clearancebetween them and entirely open at its rear end and bottom, the front endof the casing having an opening to receive the muffle, retaining-ears onsaid end of the casing to frictionally engage and hold the muffle inplace within the casing, and a handle attached to the latter.

3. In a portable dental furnace, a metallic muffle having an open mouth,a metallic, shell-like casing inclosing the muffle with a clearancebetween them for the circulation of bottom thereof, and a handleattached to the casing.

4. In a portable dental furnace, a metallic muffle having an open mouth,a casing inclosing the muffle with a clearance between them for thecirculation of flame, the casing being open at its rear end and bottomto expose the muffle to the direct flame and having a closed front endthrough which the muffle is extended and to which it is attached, theclosed end of the casing being laterally extended beyond the perimeterof the muflle, and ears on said closed end of the casing to frictionallyengage and retain the muffle in .position in the casing.

5. In a portable dental furnace, a metallic muffle having an open mouth,a casing inclosing the muffle with a clearance between them for thecirculation of flame, the casing being open at its rear end and bottomand having a closed front end through which the muffle is extended andto which it is attached, a shield projecting beyond the mouth of themuffle at the bottom thereof, ears on the closed end of the casing tofrictionally engage and hold the muflle in position in the casing, andan elongated handle secured to the casing.

6. In a portable'dental furnace, a metallic muflle having an open mouth,a metallic, semicylindrical outer casing inclosing the muffle with aclearance between them and. having an opening in its top, the rear endand bottom of the casing being open and its front end closed, means tofrictionally and detachably connect the muffle and the closed end of thecasing, and an elongated handle secured to the latter.

In testimony whereof I have signed my name to this specification in thepresence of two subscribing witnesses.

FREDERICK S. BELYEA.

Witnesses:

JOHN G. EDWARDS, ELIZABETH R. IVIORRISON.

